Interaction between Cellooligosaccharides in Aqueous Solution from Molecular Dynamics Simulation:  Comparison of Cellotetraose, Cellopentaose, and Cellohexaose

Abstract

A molecular dynamics (MD) simulation was carried out for aqueous solutions of cellooligosaccharides to investigate their interactive behavior. Single and double strands of cellotetraose, cellopentaose, and cellohexaose were simulated in systems with TIP3P water. The cellotetraose double strand separated into two within 1 ns calculation time. An aggregation state of a cellohexaose double strand is firmer than that of cellopentaose in the simulation, supporting experimental results. The self-diffusional motion of solutes is approximately in inverse proportion to their molecular surface areas without special interactive effects, while their atomic positional fluctuations manifest the effect of sugar−sugar interaction. Sugar−sugar interaction restrains the fluctuation inversely proportional to the degree of polymerization, as opposed to proportional promotion by sugar−water interaction. The degree of polymerization is at a critical point in cellopentaose, as viewed from the balance between sugar−sugar and sugar−water interaction. The occupancy of intramolecular hydrogen bonds between the particular oxygen atoms, O3 and O5‘, in adjacent residues is remarkably high in the double strand of cellohexaose among the three cellooligosaccharides, which abundance means a stable state of a twisted ribbon structure of the sugar chain. That leads to a higher occurrence of intermolecular hydrogen bonds between sugar chains using the oxygen atom O6 in cellohexaose than in cellotetraose or cellopentaose.

Simulation studies of the insolubility of cellulose

“…The assumption that cellulose chains are essentially flexible coils in solution appears to be incorrect, since both this present MD simulation, as well as others, 36,37 have suggested that the chain actually exists primarily in a single extended, twisted conformation even in solution. This rigidity reduces the supposed configurational entropy that would favor solvation over crystal packing if the chains were writhing random coils, although the solvated chains would still have greater rotational and translational freedom than in the crystal.…”

“…8) such as has been seen in other MD simulations of cellooligomers using different force fields. 36 This twist resulted when the / angles went from À98.5°to approximately À75°, and w went from À142.3°to approximately À124°. After this initial conformational change, however, the chain was quite rigid, as was also observed in previous simulations of cellooligomers.…”

“…After this initial conformational change, however, the chain was quite rigid, as was also observed in previous simulations of cellooligomers. 36,37 Figure 8 also displays the histories of the / angles for all three glycosidic linkages over the stable 10.0 ns period of the trajectory. As can be seen, with the exception of brief fluctuations, this conformation remained stable throughout the simulation.…”

Conformational properties of glucose-based disaccharides investigated using molecular dynamics simulations with local elevation umbrella sampling

“…121 Finally, the H-bond observed for C was reported in a number of previous experimental and theoretical studies. 95,111,112,120,127,128,145,221,222 In the present simulations, this specific H-bond is the one with the highest occurrence (nearly 80%). It is known to persist in the polysaccharide chains (cellulose) formed by this disaccharide in the crystalline state, 8,223 and probably represents an important determinant of the physico-chemical and mechanical properties of this material (stability, rigidity, and insolubility in water 224 ).…”

Preparation of Cellobiose-conjugated Polyacrylamide and its Interaction with a Cellulose Matrix for Papermaking Application

“…Virtually no adsorption of glucose and cellotetraose to the cellulose substrate was detected (in line with cellobiose), whereas cellohexaose showed a quite high cellulose affinity (Table). These results appear reasonable because cellohexaose inherently gathers together with time in an aqueous medium owing to its high self-assembling property via unique hydrogen bondings [17]. The number of the β-1,4-glucan units would therefore be a critical factor affecting the cellulosebinding ability of polymers containing cellooligosaccharides such as CB-A-PAM.…”